The present invention relates to a heat generator, for a vehicle, having an operation chamber defined in a housing, a viscous fluid contained in the operation chamber, and a rotor which is driven and rotated by a drive power supplied from an external drive source.
German Unexamined Patent Publication 3832966 (DE3832966A1 published on Apr. 5, 1990) discloses a heating system for occupant spaces in power vehicles with liquid-cooled internal combustion engines. The heating system will be briefly discussed below with reference to FIG. 12 which corresponds to FIG. 2 in the German publication.
The heating system has a housing which defines therein a working chamber 48 (corresponding to an operation chamber), a ring chamber 62 (corresponding to a heat receiving chamber) which surrounds the working chamber 48, and a supply chamber 58 in front of and adjacent to the working chamber 48. The supply chamber 58 and the working chamber 48 are almost completely separated from one another by a partition 60. The partition 60 is provided with a throughgoing opening 66 extending therethrough, which connects the working chamber 48 and the supply chamber 58. A connecting passage 68 is formed in the peripheral wall of the housing and at the upper edge of the partition 60 to bypass the upper portion of the partition 60. The throughgoing opening 66 is opened and closed by a lever 72 provided in the supply chamber 58. The lever 72 is biased by a coil spring 73 in a direction to open the opening 66 and is also biased by a bimetallic leaf spring 76 in a direction to close the opening 66. Namely, the open degree of the opening 66 is determined in accordance with a balance, of the biasing forces, between the springs 73 and 76.
The housing rotatably supports a drive shaft 52 at the rear portion of the housing. The drive shaft 52 is provided on its inner end with a wheel 50 (corresponding to a rotor) which is rotatable together with the drive shaft within the working chamber 48, and on the outer end thereof with a belt pulley 44 secured thereto. The belt pulley 44 is functionally connected to an engine of the vehicle through a belt. The working chamber 48 and the supply chamber 58 contain therein a predetermined amount of viscous liquid 78 with which a space defined between the outer peripheral surface 80 of the wheel 50 and the cylindrical inner wall 82 of the working chamber 48 opposed thereto is filled. Note that, as can be seen in FIG. 12, approximately the lower half of the supply chamber 58 whose opening 66 is closed by the lever 72 is filled with the viscous liquid. When the drive force of the engine is transmitted to the drive shaft 52, the wheel 50 is rotated in the working chamber 48, so that the viscous liquid reserved in the space between the outer peripheral surface 80 of the wheel and the cylindrical inner wall 82 of the working chamber is sheared, thus resulting in a generation of heat due to fluid friction. The heat generated in the working chamber 48 is transmitted to the circulation fluid (engine coolant) circulating in the ring chamber 62 through the separation wall of the housing. The heated circulation fluid is supplied to a heat exchanger of a heater for a vehicle to heat a vehicle compartment.
In the heating system mentioned above, the feed-back control of the ability to generate heat is carried out in accordance with the opening or closing operation of the opening 66 by the lever 72 whose position is controlled by the two springs 73 and 76. Concretely, when the high temperature viscous liquid is recovered in the supply chamber 58 from the working chamber 48 through the connecting passage 68, the biasing force of the bimetallic leaf spring 76 overcomes the biasing force of the coil spring 73 due to an increase in the temperature around the spring 76, so that the lever 72 closes the opening 66. Consequently, the supply of the viscous liquid from the supply chamber 58 to the working chamber 48 is suspended and, accordingly, the amount of the viscous liquid in the working chamber 48 is gradually reduced, thus leading to a reduction of the amount of heat generated by the shearing. The tendency of a decrease in temperature of the viscous liquid to be recovered from the working chamber 48 to the supply chamber 58 causes the biasing force of the bimetallic leaf spring 76 to be weakened, so that the lever 72 is moved in a direction to open the opening 66. As a result, the supply of the viscous liquid from the supply chamber 58 to the working chamber 48 starts again and hence the amount of the viscous liquid in the working chamber 48 is increased to thereby increase the amount of heat to be generated.
In order to enable the viscous liquid to flow between the supply chamber 58 and the working chamber 48 to thereby achieve the expected operation and effect of the heating system, it is necessary to mount the heating system to a vehicle body at a correct attachment angle. FIG. 11 schematically shows a cross section of the supply chamber 58 of the heating system. The correct attachment angle refers to an angle at which the opening 66 is always below the surface level L of the viscous liquid within the supply chamber 58 and the connecting passage 68 is located above the surface level L. This positional relationship between the opening 66, the passage 68 and the surface level L is a necessary condition to ensure that the opening 66 functions as a viscous fluid supply passage and that the connecting passage 68 functions as a viscous liquid recovery passage, respectively. Note that the sufficient condition to cause the movement of the viscous liquid from the supply chamber 58 to the working chamber 48 through the opening 66 is the surface level L of the viscous liquid in the supply chamber 58 being higher than the surface level of the viscous liquid in the working chamber 48. Namely, in the heating system, the drive force to move the fluid relies only upon the difference in the surface level between the two chambers 58 and 48.
However, if the heating system must be always attached to the vehicle body so as to meet the above-mentioned positional relationship of the opening 66 and the connecting passage 68, the attachment angle of the heating system has a certain limit. Namely, as shown in FIG. 11, an ideal attachment angle of the heating system is an angle (upright position) at which an imaginary plane P including the opening 66 and the connecting passage 68 is perpendicular (normal) to the surface level L, and an allowable inclination of the heating system is approximately in the range of xc2x170 degrees with respect to the upright position. Namely, the allowable attachment angle range of the heating system is limited to approximately 140 degrees about the axis C. Taking into account a possible inclination of the vehicle body itself in forward/rearward and right/left directions, the allowable attachment angle range would be smaller than 140 degrees to practically guarantee reliable operation. In the structure in which, assuming that the opening 66 and the connecting passage 68 function only as a viscous liquid supply passage and only as a viscous liquid recovery passage, respectively, in connection with other elements or members (lever 72, etc.), the single supply passage and the single recovery passage are provided, there is a drawback that the allowable attachment angle of the heating system (heat generator) is very narrow, as mentioned above, and this is not necessarily convenient for a user (car maker, etc.).
It is an object of the present invention to provide a heat generator for a vehicle in which an allowable attachment angle range of a heat generator body is increased in comparison with the prior art, the freedom of attachment to the vehicle body is enhanced, and the attachment can be facilitated.
According to the present invention, there is provided a heat generator for a vehicle comprising an operation chamber defined in a housing, viscous fluid contained in the operation chamber, and a rotor which is driven and rotated by an external drive source, characterized in that said operation chamber is comprised of a heat generation area in which said rotor is housed so as to define a liquid-tight space between a demarcation wall of the operation chamber and the rotor, so that the viscous fluid contained in the liquid-tight space is sheared, to generate heat, by the rotor, a storage area in which the viscous fluid flowing in the volume of the liquid-tight space is stored, and a boundary opening formed at a boundary between the heat generation area and the storage area to connect the heat generation area and the storage area, said boundary opening having an opening area large enough to permit the viscous fluid in the storage area to flow therethrough in accordance with the rotation of the rotor in the heat generation area; said boundary opening is provided with a plurality of transfer openings which constitute a part of the boundary opening and which permit the viscous fluid to move between the storage area and the heat generation area, said transfer openings being spaced from one another so that at least one of the transfer openings is located at a level identical to or below a surface level of the viscous fluid flowing in the storage area during the rotation of the rotor, when the heat generator is mounted to a vehicle body at an allowable attachment angle; said storage area is provided with a guide portion corresponding to each of the transfer openings to change the direction of the viscous fluid flow in the storage area to thereby introduce the viscous fluid into the heat generation area through the transfer openings, whereby the transfer opening which is located at the same level as or below the surface level of the viscous fluid flowing in the storage area and the corresponding guide portion provide a supply passage for the viscous fluid from the storage area to the heat generation area, and the remaining portion of the boundary opening other than the transfer opening which provides the supply passage provides a recovery passage of the viscous fluid from the heat generation are to the storage area, so that the exchange and circulation of the viscous fluid between the two areas can be carried out.
With this structure, since the boundary opening at the boundary between the heat generation area and the storage area is provided with a plurality of spaced transfer openings, at least one of the transfer openings is located at a level equal to or below the surface level L of the viscous fluid which moves in the storage area during the rotation of the rotor, as long as the heat generator is attached to the vehicle body at an allowable attachment angle. Consequently, the guide portion corresponding to the transfer opening that is located at a level identical to or below the surface level L is also located below the surface level L, so that the function to change the flow direction of the viscous fluid in the storage area to thereby introduce the viscous fluid into the heat generation area through the transfer opening can be achieved. Therefore, the transfer opening and the guide portion corresponding thereto, that are located at a level identical to or below the surface level L of the viscous fluid which moves in the storage area cooperate to provide a supply passage of the viscous fluid from the storage area to the heat generation area. The remaining portion of the boundary opening other than the transfer opening that constitutes the supply passage has no guide portion which corresponds thereto, and is located below the surface level L and achieves the function to change the flow direction of the viscous fluid in the storage area. In particular, the guide portions corresponding to the transfer openings other than the transfer opening that defines the supply passage, are not below the surface level L, and accordingly cannot positively achieve the function to change the flow direction of the viscous fluid. Therefore, the remaining portion of the boundary opening other than the transfer opening that constitutes the supply passage negatively provides a recovery passage of the viscous fluid from the heat generation area to the storage area. Thus, the supply passage and recovery passage of the viscous fluid are provided between the heat generation area and the storage area of the operation chamber, and the flow direction of the viscous fluid which is moved and rotated in the storage area, in accordance with the rotation of the rotor provided in the heat generation area is changed by the guide portions located below the surface level L, so that the delivery force of the viscous fluid is produced, thus resulting in the exchange and circulation of the viscous fluid between the heat generation area and the storage area of the operation chamber.
As may be seen from the foregoing, the necessary condition to ensure the exchange and circulation of the viscous fluid is to locate at least one of the plural transfer openings which constitute a part of the boundary opening at a level not higher than the surface level L. In this connection, according to the present invention, the plural transfer openings are spaced from one another in the way mentioned above, so that the probability that at least one of the transfer openings is located at or below the surface level L if the attachment angle of the heat generator to the vehicle body is variously varied can be increased. This means that the allowable attachment angle range of the heat generator can be enlarged. Consequently, with this structure, if the amount of the viscous fluid is limited to the extent that the surface level L lies in the storage area of the operation chamber, taking into account the thermal expansion of the viscous fluid in the operation chamber due to the shearing and heating, it is possible to increase the allowable attachment angle range of the heat generator in comparison with the prior art while ensuring the reliable exchange and circulation of the viscous fluid between the heat generation area and the storage area of the operation chamber. Consequently, not only can the freedom of the attachment of the heat generator to the vehicle body be enhanced but also the attachment operation can be conveniently carried out.
Note that, since the heat generation area and the storage area are interconnected by a boundary opening having a relatively large opening area, the surface level of the viscous fluid in the heat generation area is identical to the surface level L of the viscous fluid in the storage area at least at the stoppage of the rotor, so that there is basically no difference in the surface level between the two areas. Nevertheless, the viscous fluid is moved from the storage area to the heat generation area due to the presence of the guide portions provided in the storage area. In this point, the principle of the heat generator of the present invention is fundamentally distinguished from that of the prior art (heater assembly). The main purpose of the exchange and circulation of the viscous fluid in the heat generator of the present invention is to prevent or delay the deterioration of the viscous fluid.